How Stone Age blades are still cutting it in modern surgery

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Photos:How Stone Age scalpels are still cutting it in modern surgery

Obsidian -- a type of volcanic glass -- can produce cutting edges many times finer than even the best steel scalpels.

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Photos:How Stone Age scalpels are still cutting it in modern surgery

At 30 angstroms -- a unit of measurement equal to one hundred millionth of a centimetre -- an obsidian scalpel can equal diamond in the fineness of its edge.

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Photos:How Stone Age scalpels are still cutting it in modern surgery

Mesoamerican cultures such as the Mayans and the Aztecs sometimes performed human sacrifices using obsidian blades.

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Photos:How Stone Age scalpels are still cutting it in modern surgery

Unlike steel scalpels, which have a microscopically jagged edge, obsidian cleaves into a fine and continuous edge when properly cut.

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Photos:How Stone Age scalpels are still cutting it in modern surgery

Trepanation -- the practice of cutting a hole in the skull -- was performed using obsidian tools by Neolithic cultures, although its purpose remains unknown. This skull in Lausanne Museum, in France, shows signs of bone regrowth, meaning the patient survived the operation.

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Story highlights

Obsidian can produce cutting edges many times finer than even the best steel scalpels

Some surgeons still use the blades in procedures today

Vital Signs is a monthly program bringing viewers health stories from around the world.

(CNN)Ever had a headache so big, you felt like drilling a hole in your head to let the pain out?

In Neolithic times, trepanation -- or drilling a hole into the skull -- was thought to be a cure for everything from epilepsy to migraines.

It could even have been a form of emergency surgery for battle wounds.

But while there is still conjecture about the real reasons behind the mysterious procedure, what is known is that the implement often used to carry out the primitive surgery was made from one of the sharpest substances found in nature: obsidian.

Cutting edge

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Obsidian -- a type of volcanic glass -- can produce cutting edges many times finer than even the best steel scalpels.

At 30 angstroms -- a unit of measurement equal to one hundred millionth of a centimeter -- an obsidian scalpel can rival diamond in the fineness of its edge.

When you consider that most household razor blades are 300 to 600 angstroms, obsidian can still cut it with the sharpest materials nanotechnology can produce.

He explained that steel scalpels at a microscopic level have a rough cutting edge that tears into tissue, a function of the crystals that make up the metal. Obsidian, meanwhile, cleaves into a fine and continuous edge when properly cut.

Green said he once helped documentary makers produce a program on surgical technology in ancient Egyptian, setting up a blind test on the cutting power of obsidian.

Using cultured-skin burn dressing, a substance composed of skin cells, he made an incision with a modern scalpel and a parallel incision with an obsidian scalpel.

The host of the program was then invited to look at the cuts under a video microscope and tell the difference.

Cut with a chainsaw

"It wasn't hard to tell the difference at all. As soon as he turned around, everyone in the studio was like 'Ohhh,' " Green said. "Under the microscope, you could see the obsidian scalpel had divided individual cells in half, and next to it, the steel scalpel incision looked like it had been made by a chainsaw."

Modern obsidian scalpels look nothing like the decorative flint-knapped knives of Neolithic man, often resembling their modern counterparts in everything except for the blade edge, but Green said they are a very different animal.

Under the microscope you could see the obsidian scalpel had divided individual cells in half, and next to it the steel scalpel incision looked like it had been made by a chainsaw

Dr Lee Green

"The feel is very different, because obsidian has no 'bite,' " he said. "If you look under the microscope at a steel scalpel edge, it looks almost like a saw. It has teeth, whereas obsidian is smooth even microscopically.

"It's a very different feel to work with, and you have to practice before you start using it in surgery.

"You also have to be careful not to nick yourself with it, because you don't even feel it!"

And Green believes incisions made with these blades heal faster. He said a colleague who needed a mole removed agreed to undergo an experiment where half the procedure was carried out with an obsidian scalpel and the other half was removed with steel.

"What's really fun is seeing it heal," he said. "Four weeks later, the difference was quite remarkable. There was very much a difference in scarring."

Specialist use

In Germany, the manufacturer Fine Science Tools produces obsidian scalpels that can be used in situations where the patient may have an allergy to steel or metal.

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"For studies where trace metals from ordinary scalpel blades cannot be tolerated, these very special obsidian scalpels may provide the an